Drive assembly for a medication delivery device and medication delivery device

Abstract

A drive assembly for a medication delivery device is provided which is switchable from an operational state to a resetting state and which comprises: a housing having a proximal end and a distal end, a drive member adapted to be rotated with respect to the housing, and a stop member adapted to prevent rotational movement of the drive member in a first direction with respect to the housing and to permit rotational movement of the drive member in a second direction with respect to the housing, the second direction being opposite to the first direction. In the operational state of the drive assembly the stop member is held in engagement with the drive member, and for switching into the resetting state of the drive assembly the stop member is enabled to disengage from the drive member caused by gravity due to the weight of the stop member. Moreover, in the operational state of the drive assembly the drive member may be held in engagement with a rotation member, and for switching into the resetting state of the drive assembly the drive member may be enabled to disengage from the rotation member caused by gravity due to the weight of the drive member.

The invention claimed is: 
     
       1. A drive assembly for a medication delivery device being switchable from an operational state to a resetting state and comprising:
 a housing having a proximal end and a distal end, 
 a drive member adapted to be rotated with respect to the housing, 
 a stop member adapted to prevent rotational movement of the drive member in a first direction with respect to the housing in the operational state and to permit rotational movement of the drive member in a second direction with respect to the housing in the operational state, the second direction being opposite to the first direction, 
 a resilient member adapted to provide a force for engagement of the stop member and the drive member in the operational state, 
 wherein in the operational state of the drive assembly the stop member is held in engagement with the drive member, and 
 for switching into the resetting state of the drive assembly the stop member is enabled to disengage from the drive member caused by gravity due to the weight of the stop member. 
 
     
     
       2. The drive assembly according to  claim 1 , comprising a rotation member adapted to be rotated in the first direction with respect to the housing during setting of a dose of a medication and to be rotated in the second direction with respect to the housing during delivery of the dose. 
     
     
       3. The drive assembly according to  claim 2 , wherein the rotation member is arranged at an opposite side of the drive member with respect to the stop member. 
     
     
       4. The drive assembly according to  claim 2 , wherein in the operational state of the drive assembly the drive member is held in engagement with the rotation member, and for switching into the resetting state of the drive assembly the drive member is enabled to disengage from the rotation member caused by gravity due to the weight of the drive member. 
     
     
       5. The drive assembly according to  claim 2 , wherein the resilient member is adapted to provide a force for engagement of the drive member and the rotation member in the operational state. 
     
     
       6. The drive assembly according to  claim 1 , wherein the resilient member is adapted to interact with a medication receptacle of a medication delivery device such that
 when the respective medication receptacle is engaged with the housing the resilient member is strained, thereby providing the force, and 
 when the respective medication receptacle is disengaged from the housing the resilient member is unstrained, thereby not providing the force. 
 
     
     
       7. The drive assembly according to  claim 2 , wherein in the operational state the drive member is adapted to follow rotational movement of the rotation member in the second direction with respect to the housing during delivery of the dose. 
     
     
       8. The drive assembly according to  claim 7 , wherein in the operational state the drive member and the rotation member are coupled to one another by a first uni-directional friction clutch mechanism, which is configured to permit relative rotational movement between rotation member and drive member during rotation of the rotation member in the first direction for setting of the dose and to prevent relative rotational movement of rotation member and drive member during rotation of the rotation member in the second direction for delivery of the dose. 
     
     
       9. The drive assembly according to  claim 8 , wherein in the operational state the stop member and the drive member are coupled to one another by a second uni-directional friction clutch mechanism, which is configured to prevent relative rotational movement between stop member and drive member in the first direction with respect to the housing and to permit relative rotational movement of stop member and drive member in the second direction with respect to the housing. 
     
     
       10. The drive assembly according to  claim 1 , wherein in the resetting state the stop member or both the stop member and the drive member are adapted to be movable in the distal direction with respect to the housing caused by gravity, the traverse path of the respective members in distal direction with respect to the housing being delimited by mechanical stopping means. 
     
     
       11. The drive assembly according to  claim 10 , wherein the traverse path of the stop member is longer than the traverse path of the drive member. 
     
     
       12. The drive assembly according to  claim 1 , comprising a piston rod adapted to be displaced in the distal direction with respect to the housing for delivering a dose of a medication, wherein
 in the operational state of the drive assembly rotational movement of the drive member in the second direction with respect to the housing is converted into movement of the piston rod in the distal direction with respect to the housing, and 
 in the resetting state of the drive assembly rotational movement of the piston rod in the proximal direction with respect to the housing is converted into rotational movement of the drive member in the first direction with respect to the housing. 
 
     
     
       13. A medication delivery device comprising the drive assembly according to  claim 1  and a medication receptacle, the medication receptacle being removable from a housing of the drive assembly and being configured for containing at least one dose of a medication. 
     
     
       14. The medication delivery device according to  claim 13 , wherein the drive assembly comprises the drive member and a piston rod, the drive member cooperating with the piston rod for displacing the piston rod in a distal direction with respect to the housing of the drive assembly for delivering a dose of a medication, and
 wherein the device is switchable from an operational state into a resetting state by removing the medication receptacle from the housing of the drive assembly, and 
 wherein in the resetting state the piston rod is movable in a proximal direction into the housing of the drive assembly by bringing the device into a predetermined position. 
 
     
     
       15. The medication delivery device according to  claim 14 , wherein the predetermined position is a vertical position of the device with the piston rod pointing downwards. 
     
     
       16. The drive assembly according to  claim 1 , wherein in the resetting state of the drive assembly the stop member and the drive member are disengaged such that the drive assembly becomes resettable and a resetting movement of the drive member in the first direction can be performed. 
     
     
       17. The drive assembly according to  claim 1 , wherein the stop member is rotationally fixed in the housing. 
     
     
       18. The drive assembly according to  claim 2 , further comprising a piston rod configured to be displaced in the distal direction with respect to the housing for delivering a dose of a medication responsive to the drive member rotating in the second direction,
 wherein the piston rod is distinct from the rotational member. 
 
     
     
       19. The drive assembly according to  claim 1 ,
 wherein a disengagement of the stop member from the drive member is realized under gravity such that no further elements are necessary for separating the stop member from the drive member. 
 
     
     
       20. A drive assembly for a medication delivery device being switchable from an operational state to a resetting state and comprising:
 a housing having a proximal end and a distal end, 
 a drive member adapted to be rotated with respect to the housing, and 
 a stop member adapted to prevent rotational movement of the drive member in a first direction with respect to the housing in the operational state and to permit rotational movement of the drive member in a second direction with respect to the housing in the operational state, the second direction being opposite to the first direction, 
 wherein in the operational state of the drive assembly the stop member is held in engagement with the drive member, and 
 for switching into the resetting state of the drive assembly the stop member is enabled to disengage from the drive member caused by gravity due to the weight of the stop member 
 wherein a disengagement of the stop member from the drive member is realized under gravity such that no further elements are necessary for separating the stop member from the drive member.